A conventional inspection apparatus includes, for example, as shown in FIG. 5, a movable mounting table 1 for mounting an object to be inspected (e.g., a semiconductor wafer), a driving unit 2 for horizontally and vertically moving the mounting table 1, a probe card 3 provided above the mounting table 1, an alignment unit 4 for performing a position alignment of probes 3A of the probe card 3 with electrode pads of a semiconductor wafer W mounted on the mounting table 1, and a controller 5 for controlling various components including the mounting table 1 and the alignment unit 4. A position alignment of the electrode pads of the semiconductor wafer W mounted on the mounting table 1 with the probes 3A of the probe card 3 is performed under control of the controller 5 such that the electrode pads are made to be in contact with the probes 3A. Then, the semiconductor wafer W is overdriven to inspect electrical characteristics of the semiconductor wafer W by a specific contact load.
The driving unit 2 includes a servo motor for driving an XY stage and a stepping motor forming an elevation drive unit for vertically moving the mounting table 1. The alignment unit 4 includes a first camera 4A for imaging the semiconductor wafer W mounted on the mounting table 1, a second camera 4B for imaging the probes 3A of the probe card 3, and image processing parts 4C and 4D for processing images obtained by the first and second cameras 4A and 4B, respectively. The position alignment is performed based on the images of the electrode pads of the semiconductor wafer W and the probes 3A of the probe card 3. Further, in FIG. 5, a reference numeral ‘4E’ designates an alignment bridge.
For example, when a high temperature inspection is performed on the semiconductor wafer W, the semiconductor wafer W mounted on the mounting table 1 is heated to a temperature of, e.g., 150° C. by using a temperature control device embedded in the mounting table 1 and an alignment of the electrode pads of the semiconductor wafer W mounted on the mounting table 1 with the probes 3A of the probe card 3 is performed by using the alignment unit 4. The mounting table 1 is moved up by using the elevation drive unit having the stepping motor such that the electrode pads are made to be in contact with the probes 3A. Then, the semiconductor wafer W is overdriven such that the electrode pads are made to be in electrical contact with the probes 3A with a specific contact load. Then, the electrical characteristics of the semiconductor wafer W are inspected at the high temperature of 150° C.
In the initial step of the inspection, the semiconductor wafer W is heated to the high temperature of 150° C., but the probe card 3 is not heated. Accordingly, there is a large temperature difference between the semiconductor wafer W and the probes 3A. Thus, when the probes 3A are made to be in contact with the electrode pads of a first device of the semiconductor wafer W in the inspection, the probes 3A are heated directly by the semiconductor wafer W mounted on the mounting table 1 and thermally expanded. Further, a main body of the probe card 3 is also gradually heated and thermally expanded by heat dissipated from the semiconductor wafer W. The temperatures of the main body and the probes 3A of the probe card 3 gradually rise while the inspection is repeatedly performed on the devices of the semiconductor wafer W. The probes 3A are extended from a state shown in FIG. 6A or a state represented by a fine line in FIG. 6B to a state represented by a solid line in FIG. 6B, and tip positions of the probes 3A are gradually lowered from their initial positions. Accordingly, if the semiconductor wafer W is overdriven by a predetermined overdrive amount through the stepping motor, the contact load between the probes 3A and the semiconductor wafer W exceeds an appropriate contact load, resulting in a worrisome possibility of damaging the probes 3A or the electrode pads P. Further, it takes a long time until the probe card 3 is thermally expanded and the tip positions of the probes 3A are stabilized.
As a result, when a high temperature inspection is performed, the probe card is preheated and completely thermally expanded in advance to stabilize its dimension before the high temperature inspection is performed. However, as the size of the probe card increases, time required for preheating becomes long, for example, 20 to 30 minutes. Accordingly, for example, in a technology disclosed in Japanese Patent Laid-open Publication No. 2007-088203, the probes are made to be in direct contact with the semiconductor wafer set at a high temperature in the inspection, and the probe card is preheated from the vicinity of the probe card.
However, in the technology disclosed in the Publication, the probe card is hardly thermally expanded during the high temperature inspection, and the probe is made to be in contact with the semiconductor wafer with a stable contact load by overdriving the semiconductor wafer, thereby preventing the probe card or the semiconductor wafer from being damaged. However, since preheating time of the probe card is required in addition to inspection time, there has been a problem that the inspection time becomes long by the preheating time. Further, if the probe card is not preheated, the tip positions of the probes 3A are lowered during the inspection as described above to cause an excessive contact load, resulting in a worrisome possibility of damaging the devices of the semiconductor wafer W or the probe card 3.